Engine-powered walk-behind working machines are often operated in dusty conditions. Working in a dusty environment, an engine air intake system of the working machine needs an effective countermeasure against dust ingestion. In case of an engine-powered lawnmower, dust and grass clippings generated during mowing operation may cause clogging of an air-cleaner element of the engine air intake system, resulting in a premature lawnmower engine failure. It is therefore advisable to take appropriate measures to avoid clogging of the air-cleaner element.
Examples of such anti-clogging measures proposed heretofore are disclosed in Japanese Utility Model Laid-Open Publication (JP-U) No. 62-59754 and Japanese Patent Laid-Open Publication (JP-A) No. 7-247927, which employ a so-called “snorkel air-cleaner structure” having an air inlet opening disposed adjacent to a handlebar of the working machine at a position far away from the ground surface in order to introduce fresh air into an air-cleaner, and a hose connecting the air inlet opening to the air-cleaner.
The snorkel air-cleaner structure shown in JP-U 62-59754 is incorporated in an engine-powered bush cutter including an engine, an air intake system for the engine, and an operation handle. The air intake system includes an air-cleaner mounted on the engine, an air intake portion (snorkel) mounted on the handle, and a hose that introduces the outside air from the air intake portion into the air-cleaner.
The snorkel air-cleaner structure disclosed in JP-A 7-247927 is incorporated in an engine-powered lawnmower having an engine, an air intake system for the engine, and an operation handle. The air intake system includes an air-cleaner mounted on the engine, an air intake portion mounted on the handle, and a fresh air intake conduit that introduces the outside air from the air intake portion into the air-cleaner.
The working machines such as bush cutters or lawnmowers are usually used outdoors and sometimes washed with water. This will require the air intake system to have appropriate means for preventing water ingestion, which may otherwise occur when the working machines are subjected to rainfall or washed with water. In order to secure a desired performance of the air-cleaner, care must be taken to keep the air-cleaner from deterioration by water ingestion occurring at the air inlet opening. Thus, there is still room for improvement in the conventional engine air intake system having a snorkel air-cleaner structure.
It is therefore an object of the present invention to provide an engine air intake system for an engine-powered walk-behind working machine having a snorkel air-cleaner structure, which is highly resistant to both of dust ingestion and water ingestion.